An Analysis of Natural Fiber Composite Processing Conditions

摘要

Composite structures have been used to replace traditional materials in many different applications. Fiberglass epoxy systems have been utilised for boat construction for many years. In the past 20 years carbon fiber has replaced aluminum for lightweight high strength applications in sporting equipment from hockey sticks to Formula 1 racecars. New developments are investigating the use of natural fiber composite materials in domestic and industrial applications. Such materials are already used in applications like panels, ceilings, partition boards, packaging, automobile interiors, storage devices and railway coach interiors. An example of a natural fiber composite is in the BMW Series 5 door linings where it has been used for sound dampening and improved side impact protection. Composites are lightweight, have a high strength to weight ratio and good stiffness. Composites are increasingly being used to replace conventional materials like metal and wood. Natural fiber reinforcement materials for composites are an attractive alternative to wood, metal and man made fibers due to their low cost, renewable nature and biodegradability. This paper looks at 5 different natural fiber composites made using a thermosetting epoxy resin. The fibers investigated were coir, sisal, hemp, kenaf and flax. Fiber width and fiber length were measured for each of the fibers to allow for comparison of fiber properties towards composite properties. Reinforcing fiber selection, hardener type and resin to fiber ratio were analyzed with reference to void content, tensile strength, shear strength and water absorption. It was found that the hemp fiber had the best fiber properties for a composite (long length and small fiber width). The sisal had the lowest void content of 0.44%. The hemp fiber also had a low void content (0.73%). The flax fiber possessed the best tensile modulus (10534 MPa). The hemp and the sisal performed better than the coir in shear strength (Sisal 7.21 MPa and Hemp 7.25Mpa). The hemp had the best water absorption performance (1.37%). The fast hardener performed better in tensile performance than the slow hardener.